CN113993723A

CN113993723A - Tyre for vehicle wheels

Info

Publication number: CN113993723A
Application number: CN202080042310.3A
Authority: CN
Inventors: 长谷川圭一; 有马正之
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 2019-06-18
Filing date: 2020-06-10
Publication date: 2022-01-28
Also published as: US20220314707A1; EP3988345A1; EP3988345A4; WO2020255831A1; JP2020203612A

Abstract

The tire has a bead structure (61), and the bead structure (61) includes: a bead core (62) having a cord unit (63); and a bead filler (69) that is connected to the bead core (62) on the outer side of the bead core (62) in the tire radial direction, and that is formed of a resin material. The bead filler (69) has a tip end portion (69a) that narrows toward the outside in the tire radial direction. The tip (69a) is located further inward in the tire width direction than a straight line (L1) passing through the center (62a) of the inner end of the bead core (62) in the tire radial direction in the width direction and the center (62b) of the outer end of the bead core in the tire radial direction in the width direction.

Description

Tyre for vehicle wheels

Technical Field

The present invention relates to a tire in which a part of a bead portion is formed of a resin material.

Background

Conventionally, a tire in which a space portion of a bead core is filled with a resin has been known (see patent document 1).

This can reduce the amount of the metal bead cord, and thus can reduce the weight of the tire.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2002-187414

Disclosure of Invention

As described above, the weight of the tire can be reduced by partially replacing the structural member of the tire with a resin (or a rubber), but the following problems are present.

For example, a filler-integrated resin bead structure in which a bead core coated with a resin material using a bead cord and a bead filler made of resin are integrally molded is considered.

However, such a resin bead structure has higher rigidity than a conventional rubber body bead core and bead filler, and is less likely to deform even during vulcanization of a green tire.

Therefore, the resin bead structure cannot follow the deformation of the rubber main body member such as the carcass ply, and air is likely to be mixed into the gap between the resin bead structure and the other member, thereby deteriorating the yield.

The present invention has been made in view of such circumstances, and an object thereof is to provide a tire using a resin bead structure in which a bead core in which a bead cord is covered with a resin and a bead filler made of a resin are integrally molded without deteriorating yield.

One aspect of the present disclosure is a tire, including: a tread portion that contacts a road surface; a sidewall portion that is connected to the tread portion and is located on a tire radial direction inner side of the tread portion; and a bead portion that is continuous with the side portion and is located on a tire radial direction inner side of the side portion, wherein the tire is provided with a carcass ply forming a skeleton of the tire, the bead portion having a bead structure including: a bead core having bead cords; and a bead filler, which is connected to the bead core on the outer side in the tire radial direction of the bead core, is formed of a resin material, and has a tip end portion that narrows as going toward the outer side in the tire radial direction, the tip end portion being located on the inner side in the tire width direction than a straight line passing through a center in the width direction of an inner end in the tire radial direction of the bead core and a center in the width direction of an outer end in the tire radial direction of the bead core.

Drawings

Fig. 1 is a sectional view of a pneumatic tire 10.

Fig. 2 is a partially enlarged sectional view of the pneumatic tire 10.

Fig. 3 is a single cross-sectional view of the bead structure 61.

Fig. 4 is a view schematically showing a manufacturing process of the pneumatic tire 10.

Fig. 5 is a single cross-sectional view of the bead structure 61X.

Detailed Description

The drawings are described below based on embodiments. In addition, the same or similar reference numerals are given to the same functions and structures, and the description thereof is appropriately omitted.

(1) General structure of tire as a whole

Fig. 1 is a sectional view of a pneumatic tire 10 of the present embodiment. Specifically, fig. 1 is a cross-sectional view of the pneumatic tire 10 along the tire width direction and the tire radial direction. Note that, in fig. 1, the hatching of the cross section is not shown (the same applies hereinafter).

As shown in fig. 1, the pneumatic tire 10 includes a tread portion 20, a sidewall portion 30, a carcass ply 40, a belt layer 50, and a bead portion 60.

The tread portion 20 is a portion that comes into contact with a road surface (not shown). A pattern (not shown) corresponding to the usage environment of the pneumatic tire 10 and the type of vehicle to which the pneumatic tire is mounted is formed in the tread portion 20.

The sidewall portion 30 is connected to the tread portion 20 and is located on the tire radial direction inner side of the tread portion 20. The side portion 30 is a region from the tire width direction outer end of the tread portion 20 to the upper end of the bead portion 60. The sidewall portion 30 may be referred to as a sidewall or the like.

The carcass ply 40 forms the carcass of the pneumatic tire 10. The carcass ply 40 is a radial structure in which carcass cords (not shown) radially arranged in the tire radial direction are covered with a rubber material. However, the present invention is not limited to the radial structure, and may be a bias structure in which the carcass cords are arranged so as to cross in the tire radial direction.

The carcass cord is not particularly limited, and can be formed of an organic fiber cord substantially similar to a tire for a general passenger car (including a van vehicle, suv (sport Utility vehicle)).

The belt layer 50 is provided on the tire radial direction inner side of the tread portion 20. The belt layer 50 is a single-layer spiral belt having a reinforcing cord 51 (see also fig. 2) and the reinforcing cord 51 is coated with a resin. However, the belt layer 50 is not limited to a single-layer spiral belt. For example, the belt layer 50 may be a double-layer cross belt covered with rubber.

The reinforcing cord 51 may be formed of a monofilament (single strand) such as a metal fiber or an organic fiber, or a multifilament (multiple strand) obtained by twisting these fibers. In the present embodiment, a steel cord can be used as the reinforcing cord 51.

The resin for covering the reinforcing cord 51 is a resin material having a higher tensile elastic modulus than the rubber material for the sidewall 30 and the rubber material for the tread 20. As the resin for covering the reinforcing cord 51, a thermoplastic resin, a thermoplastic elastomer (TPE), a thermosetting resin, or the like having elasticity can be used. In consideration of the elasticity during running and the formability during production, a thermoplastic elastomer is preferably used.

Examples of the thermoplastic elastomer include polyolefin thermoplastic elastomer (TPO), polystyrene thermoplastic elastomer (TPS), polyamide thermoplastic elastomer (TPA), polyurethane thermoplastic elastomer (TPU), polyester thermoplastic elastomer (TPC), and dynamic cross-linked thermoplastic elastomer (TPV).

Examples of the thermoplastic resin include a polyurethane resin, a polyolefin resin, a polyvinyl chloride resin, and a polyamide resin. Further, as the thermoplastic resin material, for example, a material having a deflection temperature under load (under a load of 0.45 MPa) of 78 ℃ or higher as specified in ISO75-2 or ASTM D648, a tensile yield strength of 10MPa or higher as specified in JIS K7113, a tensile elongation at break of 50% or higher as specified in JIS K7113, and a Vicat softening temperature (method A) of 130 ℃ or higher as specified in JIS K7206 can be used.

The bead portion 60 is connected to the sidewall portion 30 and is located on the tire radial direction inner side of the sidewall portion 30. The bead portion 60 is annular extending in the tire circumferential direction.

A part of the bead portion 60 is made of a resin material. In the present embodiment, a part of the bead portion 60 is formed of the same resin material as that used for the above-described belt 50.

The bead portion 60 is engaged with a flange portion 110 (not shown in fig. 1, see fig. 2) formed at a radially outer end of the wheel rim 100.

An inner liner (not shown) is bonded to the tire inner surface of the pneumatic tire 10, and prevents air (or gas such as nitrogen) filled in the inner space of the pneumatic tire 10 assembled to the wheel rim 100 from leaking.

(2) Schematic structure of bead unit

Fig. 2 is a partially enlarged sectional view of the pneumatic tire 10. Specifically, fig. 2 is a partially enlarged cross-sectional view of the pneumatic tire 10 along the tire width direction and the tire radial direction, including the bead portion 60.

As shown in fig. 2, the carcass ply 40 is folded back to the outside in the tire width direction via the bead portion 60. Specifically, the carcass ply 40 includes a main body portion 41 and a turnback portion 42.

The main body portion 41 is a portion provided astride the tread portion 20, the sidewall portion 30, and the bead portion 60 and folded back at a bead core 62 of the bead portion 60.

The folded-back portion 42 is a portion that is continuous with the main body portion 41 and is folded back toward the outer side in the tire width direction via the bead core 62.

The bead unit 60 has a bead structure 61. In the present embodiment, the bead structure 61 is a structure in which the bead core 62 (including the peripheral portion of the cord unit 63) and the bead filler 69 are integrally formed. That is, the bead portion 60 has a bead core 62 and a bead filler 69.

Further, the bead core 62 and the bead filler 69 may not necessarily be integrally formed from before the manufacture of the pneumatic tire 10. That is, the separate resin bead core 62 and bead filler 69 may be bonded and integrated at the time of manufacture.

A rim line 90 is provided on the tire width direction outer side surface of the bead portion 60. The rim line 90 is a convex portion formed along the tire circumferential direction to confirm whether or not the bead portion 60 is properly mounted on the wheel rim 100. In the present embodiment, the rim line 90 is provided at a position that is about 6mm outside the tire radial direction outer end of the flange portion 110 in the tire radial direction.

In the present embodiment, the tire radial direction outer end of the bead filler 69 is located further inward in the tire radial direction than the rim line 90 and the tire radial direction outer end of the flange portion 110.

The tire radial direction outer end of the folded-back portion 42 is located further toward the tire radial direction outer side than the rim line 90 and the tire radial direction outer end of the flange portion 110, and extends to the sidewall portion 30.

(3) Detailed structure of bead unit

Fig. 3 is a single cross-sectional view of the bead structure 61. Specifically, fig. 3 is an enlarged cross-sectional view of the bead structure 61 of the pneumatic tire 10 along the tire width direction and the tire radial direction. As shown in fig. 3, the bead structure 61 includes a bead core 62 and a bead filler 69.

The bead core 62 comprises cord units 63. The cord unit 63 includes a plurality of bead cords 63 a. The bead cord 63a is formed of a metal material such as steel. The cord unit 63 is formed by covering the bead cord 63a with a resin material. In other words, the bead core 62 is formed by covering the bead cord 63a with a resin material.

In the present embodiment, the bead cord 63a is provided so as to have a structure of 4 × 3 (tire radial direction × tire width direction). Further, the bead cord 63a is not particularly twisted, but one or a plurality of (e.g., three in the tire width direction) bundled bead cords 63a are wound a plurality of times in the tire circumferential direction.

The bead core 62 and the bead filler 69 are integrally formed using a resin material. Specifically, the bead core 62 (except for the bead cords 63 a) and the bead filler 69 are formed using a resin material. As the resin material, the same resin material as that used for the belt 50 can be used.

However, the bead core 62 and the bead filler 69 may not necessarily be formed of the same resin material as that used for the belt 50. That is, as long as the above-described resin material can be used for the belt 50, the resin material used for the belt 50, the bead core 62, and the bead filler 69 may be different.

The bead filler 69 has a tip end portion 69a that narrows as it goes outward in the tire radial direction. The bead filler 69 narrows as it approaches the distal end portion 69a so as to fill a gap between the main body portion 41 and the folded-back portion 42 of the carcass ply 40. The bead filler 69 may be tapered toward the tip end portion 69a in a cross-sectional view taken along the tire width direction and the tire radial direction.

The tip end portion 69a is an apex portion of the bead filler 69. The tip end 69a is offset inward in the tire width direction from the center of the bead structure 61 in the width direction (substantially, the tire width direction).

Specifically, the tip end 69a is located on the inner side in the tire width direction than a straight line L1 passing through the center 62a of the tire radial direction inner end of the bead core 62 (here, the cord unit 63) and the center 62b of the tire radial direction outer end of the bead core 62 in the width direction.

In the present embodiment, the distal end portion 69a is located within 30% of the entire width (width W1 in the drawing) from the inner end 61a of the bead structure 61 in the tire width direction to the outer end 61b of the bead structure 61 in the tire width direction. Specifically, the tip end portion 69a is located within the range of the width W2. The width W2 is based on the inward end 61 a.

(4) Outline of the method for manufacturing the pneumatic tire 10

Next, a schematic description will be given of a method for manufacturing the pneumatic tire 10. Fig. 4 schematically shows a manufacturing process of the pneumatic tire 10. Specifically, fig. 4 shows a state in which the unvulcanized tread rubber 20P, the carcass ply 40, the belt 50, and the bead structures 61 are arranged before vulcanization of the pneumatic tire 10.

The carcass ply 40 is folded back via the bead structures 61. The main body portion 41 of the carcass ply 40 is positioned on the inner side in the tire width direction of the bead structure 61. On the other hand, the folded-back portion 42 of the carcass ply 40 is positioned on the outer side in the tire width direction of the bead structure 61.

The folded portion 42 is folded back from the tire width direction outer side toward the tire width direction inner side (see an arrow in the drawing), and the bead structure 61 also approaches the main body portion 41. At this time, air is particularly likely to remain in the region a1, and this is known to cause so-called air entrainment.

On the other hand, it is also found that the region a2 is less likely to cause air entrainment than the region a 1. Therefore, in the present embodiment, as described above, the bead filler 69 has a shape in which the tip end portion 69a (see fig. 3) is offset inward in the tire width direction from the center of the bead structure 61 in the width direction.

In particular, the resin bead structure 61 (excluding the cord unit 63) including the bead filler 69 has a property that it is hard to soften in the vulcanization step and hard to change in shape, as compared with the rubber member. Therefore, compared to a conventional bead structure such as a bead filler mainly made of a rubber material, the following property and adhesiveness to other rubber members such as the carcass ply 40 are low, and particularly, air inclusion is likely to occur.

In the present embodiment, the use of the bead structures 61 having the above-described shape effectively suppresses air entrainment.

(5) Other examples of the shape of the bead structure

The shape of the bead structure 61 described above is an example, and the following shape may be used. Fig. 5 shows another example of the shape of the bead structure. Specifically, fig. 5 is a single cross-sectional view of the bead structure 61X.

The bead structure 61X can be used as a substitute for the bead structure 61, but whichever of the bead structure 61 and the bead structure 61X is used can be appropriately selected in accordance with the specification, the aspect ratio, and the like of the pneumatic tire 10.

As shown in fig. 5, in the bead structure 61X, the tip end portion 69a of the bead filler 69 is also offset inward in the tire width direction from the center of the bead structure 61X in the width direction.

In the bead structure 61X, the distal end portion 69a is further shifted inward in the tire width direction. Specifically, the tip end portion 69a is located further inward in the tire width direction than an inner end 69b in the width direction of the bead filler 69 on a straight line L2 passing through the inner end of the bead filler 69 in the tire radial direction.

The inner end of the bead filler 69 in the tire radial direction is a boundary between the bead core 62 and the bead filler 69 when the bead core 62 and the bead filler 69 are separate bodies before manufacture and the boundary therebetween is clear, but the inner end may be a position where the width of the bead structure 61X starts to be narrowed when the bead core 62 and the bead filler 69 are integrally formed as in the present embodiment.

That is, the tip end 69a of the bead structure 61X is located further inward in the tire width direction than the tire width direction inner end of the portion of the bead core 62. Since the bead filler 69 of the bead structure 61X is in such a positional relationship of the tip end portion 69a, the cross-sectional shape of the bead structure 61X is curved inward in the tire width direction.

In the bead structure 61X, the tip end 69a is also located within 30% of the width W1 of the bead structure 61X (width W2 in the figure).

(6) Action and Effect

According to the above embodiment, the following operational effects are obtained. Specifically, in the bead structure 61 and the bead structure 61X, the tip end portion 69a of the bead filler 69 is offset inward in the tire width direction from the center of the bead structure 61X in the width direction.

Therefore, since the gap with the body portion 41 side of the carcass ply 40 is narrowed in the manufacturing process, air is less likely to remain in the region a1 (see fig. 4) in the manufacturing process of the pneumatic tire 10 as described above. That is, air can be effectively prevented from being mixed in.

That is, it is possible to manufacture a tire using a resin-made bead structure in which a bead core 62 (cord unit 63) in which a bead cord 63a is covered with a resin is integrally molded with a bead filler 69 made of a resin without deteriorating yield.

In the present embodiment, like the bead structure 61X (see fig. 5), the tip end 69a may be located further inward in the tire width direction than the inner end 69b in the tire width direction of the bead filler 69 on the straight line L2 passing through the inner end of the bead filler 69 in the tire radial direction.

Therefore, an appropriate shape of the bead structure that can effectively suppress air inclusion can be appropriately selected according to the specification, the aspect ratio, and the like of the pneumatic tire 10. In particular, it is considered that the bead structure 61X is easily applied to a pneumatic tire having a low aspect ratio.

In the present embodiment, the distal end portion 69a is located in a region within 30% of the width W1 of the bead structure 61 (or the bead structure 61X). Therefore, an appropriate displacement of the tip end portion 69a that can suppress air entrainment can be imparted to the bead structure.

In addition, in the present embodiment, the bead core 62 (cord unit 63) is formed by covering the bead cord 63a with a resin material. Thus, even in the case of using the bead core 62 in which the bead cord 63a is covered with the resin, air inclusion can be effectively suppressed, and the yield is not deteriorated.

(7) Other embodiments

While the present invention has been described with reference to the above examples, it will be apparent to those skilled in the art that the present invention is not limited to these descriptions, and various modifications and improvements can be made.

For example, in the above-described embodiment, the bead core 62 uses the cord unit 63 formed by covering the bead cord 63a with the resin material, but the bead cord 63a may not be covered with the resin material. Also in this case, the bead cord may be composed of a multi-strand wire.

In the above-described embodiment, the bead cord 63a has a 4 × 3 (tire radial direction × tire width direction) configuration, but may have other configurations, for example, 3 × 3 or 4 × 4.

While the embodiments of the present invention have been described above, it should not be understood that the discussion and drawings constituting a part of this disclosure limit the present invention. Various alternative implementations, embodiments, and operational techniques will be apparent to those skilled in the art in light of this disclosure.

Description of the reference numerals

10. A pneumatic tire; 20. a tread portion; 20P, tread rubber; 30. a sidewall portion; 40. a carcass ply; 41. a main body portion; 42. a fold-back portion; 50. a belt ply; 51. a reinforcing cord; 60. a bead portion; 61. a bead structure; 61a, an inner end; 61b, an outer end; 61X, bead structure; 62. a bead core; 62a, 62b, center; 63. a cord unit; 63a, bead cord; 69. a bead filler; 69a, a tip end portion; 69b, an inner end; 90. a rim line; 100. a wheel rim; 110. a flange portion.

Claims

1. A tire, comprising:

a tread portion that contacts a road surface;

a sidewall portion that is connected to the tread portion and is located on a tire radial direction inner side of the tread portion; and

a bead portion that is connected to the sidewall portion and is located on a tire radial direction inner side of the sidewall portion, wherein,

the tire is provided with a carcass ply forming a framework of the tire,

the bead portion has a bead structure including:

a bead core having bead cords; and

a bead filler joined to the bead core at a tire radial direction outer side of the bead core, formed of a resin material,

the bead filler has a tip end portion that narrows as going toward the outer side in the tire radial direction,

the tip portion is located on the inner side in the tire width direction than a straight line passing through the center of the inner end in the tire radial direction of the bead core and the center of the outer end in the tire radial direction of the bead core in the width direction.

2. The tire according to claim 1, wherein,

the tip end portion is located further inward in the tire width direction than a widthwise inner end of the bead filler on a straight line passing through the tire radial direction inner end of the bead filler.

3. The tire according to claim 1 or 2,

the tip end portion is located in a region within 30% of the entire width from the tire width direction inner end of the bead structure to the tire radial direction outer end of the bead structure.

4. A tire according to any one of claims 1 to 3,

the bead core is formed by coating the bead cord with a resin material.